This is cool, the concept is kinda similar to what I did.
The game starts lagging after a while (only a bit) and the audio becomes a bit crackly. My mouse inputs sometimes didn't register, maybe because the game unresposive during that time (not sure tho). Also I managed to softlock myself by clearing the screen before the lasers fire for the first time and getting a laser in the evil turn, an undo last placement would be nice (also for if/when you make it impossible for yourself). Ok last thing, a turn counter would have been cool.